Can i keep the registration of my car even if it is not a personalised plate?

In the UK you can. You can even keep the reg number on retainer if you do not have another car to move it too. The only thing you can't du is to put a newer reg number on an older car to make it look newer. If you go to the DVLA website they have all the forms there.

You can transfer most registrations between different vehicles.
The only exceptions are where the registration document states "not transferable" - this will happen, for example, when the original registration has been restored to a classic car.
Also, you cannot transfer a registration with an age-identifier (a year letter, or the newer year number) on to a car older than the issue of that registration (you cannot transfer a 56 reg onto a 51-reg car, but you can transfer a 51-reg onto a 56-reg car). More Questions & Answers ...